Display screen or portion thereof with transitional graphical user interface



FIG. 1 is a first image in a sequence for a display screen or portionthereof with transitional graphical user interface showing our newdesign in accordance with a first embodiment;

FIG. 2 is a second image thereof;

FIG. 3 is a third image thereof;

FIG. 4 is a fourth image thereof;

FIG. 5 is a first image in a sequence for a display screen or portionthereof with transitional graphical user interface showing our newdesign in accordance with a second embodiment;

FIG. 6 is a second image thereof;

FIG. 7 is a third image thereof; and,

FIG. 8 is a fourth image thereof.

The appearance of the transitional image sequentially transitionsbetween the images shown in FIGS. 1-4 and FIGS. 5-8. The process orperiod in which one image transitions to another forms no part of theclaimed design. The outermost broken lines in the figures depict adisplay screen or portion thereof and form no part of the claimeddesign. The remainder of the broken lines in the figures depictsportions of the transitional graphical user interface that form no partof the claimed design.

CLAIM The ornamental design for a display screen or portion thereoftransitional graphical user interface, as shown and described.